FI67259C - VENTILATIONSSYSTEM. - Google Patents

Description

67259

Air Conditioning system

The invention relates to an air conditioning system in which the supply air is passed through a heat exchanger and the exhaust air is led through the same heat exchanger in the opposite direction. The purpose of this generally known arrangement is to recover heat from the exhaust air. In summer there is no need for this, on the contrary, it is usually desired to cool the supply air.

10 A known type of cooling is the use of heat pump compressor units. When the volumes of air to be treated are generally large, the compressor machinery becomes large and its both acquisition and operating costs, namely the consumption of electrical power, are high.

15 Another known type of cooling is humidification of the air.

The cooling effect is based on the high heat of vaporization of the water. As it evaporates, water traps heat from the air and cools it. The weakness of the method is that the relative humidity of the air increases. High humidity easily causes damage to buildings, furniture, etc. and creates favorable growth conditions for molds, bacteria, etc., which increases the risk of damage to structures and furniture and poses health risks to people. In addition, the actual cooling effect remains less than 25 directly from the temperature drop one could imagine. Namely, human temperature control is based on evaporation, i.e. sweating. High humidity makes it hard to sweat, and the wetter the air, the hotter it feels. Studies have shown that a temperature of 25 ° C at 100% relative humidity and 30 ° C at 50% relative humidity is considered to be the same temperature. Nevertheless, humidification-based cooling is commonly used, for example, in industry, when the volume flows to be treated are so high that the cost of compressor cooling would become unreasonable. It is also common in countries where the air is very dry (so-called desert cooler). In practice, it has been found that, in addition to the fundamental weaknesses mentioned above, it is almost impossible to adjust the system.

This is due to the fact that the desired result, i.e. the air blowing temperature, is influenced by too many non-interdependent factors, namely the supply air temperature, the supply air humidity, the water temperature and the degree of humidification, which in itself is very difficult to control. The main advantages of the system are the simple structure and, as a result, the low price and low operating costs.

The object of the invention is to provide a new air conditioning system on the basis of the system presented at the beginning, in which a heat exchanger is used, if necessary, to cool the supply air.

The object is achieved by means of an air conditioning system according to the invention, characterized in that a humidification section is arranged in the exhaust air flow path before the heat exchanger to cool the flowing air by evaporating water vapor and through which at least part of the exhaust air can be led.

The system of the invention is thus based on economically advantageous humidification, but does not have the disadvantages of known humidification cooling systems. The basic idea is not to humidify the supply air directly, but to use exhaust air, which is humidified and thus uses cooled air to cool the supply air. In this case, the humidity of the air conditioning air does not increase and the disadvantages caused by humidity are avoided. The adjustment is considerably easier, as instead of humidification, mass flows can be adjusted and dew point humidification can be used at all times.

In this patent application, the term "exhaust air" generally means air which flows through the heat exchanger in the opposite direction to the supply air; in the cooling situation where the heat load of the room to be ventilated is so high that the temperature of the air leaving the room is higher than the supply air temperature, it is preferable to blow the actual exhaust air directly out and instead return part of the supply air back to the heat exchanger.

3 67259

In a particularly preferred embodiment of the invention, the humidification part included in the system is used in winter to humidify the supply air when the outdoor air is very dry.

In this case, the exhaust air is led directly to the heat exchanger and the 5 supply air is led to the air-conditioned space partly or completely through the humidification section.

Em. implementations are defined in claims 3-5 and are also apparent from the following detailed description with reference to the accompanying drawing.

Figure 1 shows diagrammatically the basic solution of the system according to the invention.

Figures 2 and 3 show variations of the solution of Figure 1.

Figure 4 shows a particularly preferred embodiment of the invention.

In the exemplary embodiments of the drawing, the supply air flow is indicated by reference numeral 1 and the exhaust air flow by reference numeral 2, and the corresponding fans by reference numerals 3 and 4. Numeral 5 indicates a heat exchanger through which the supply and exhaust air flow in opposite directions. 6 is a humidification section placed in front of the heat exchanger, where the exhaust air is cooled by evaporating water vapor therein through nozzles 7. With the air thus cooled, the supply air is cooled in the heat exchanger 5, which flows from here through the pipe 8 25 to a space to be further treated or air-conditioned.

The cooling output is controlled by a thermostat 9 placed in the duct 8, which controls the control motor 11 of the damper 10. The basic solution shown in Fig. 1 can of course vary, the damper 10 can be located between the humidifier 6 30 and the heat exchanger 5 or . Likewise, the location of the fans 3 and 4 in the system is freely selectable, etc.

Instead of the damper 10, another auxiliary 35 can be used without adjusting the amount. For example, the damper can be replaced with a guide vane regulator or by using an adjustable vane fan, by adjusting the fan speed, etc.

67259 The adjustment can also be performed by bypassing the heat exchanger. Such a solution is shown in Figure 2. The system operates in the same way as shown in Figure 1, but the damper 10 has been transferred to the air-conditioning air duct and a bypass control damper 12 and a bypass duct 13 have been added to the system-5.

The motor 14 simultaneously adjusts the dampers 10 and 12, which are cross-connected so that when the damper 10 opens, the damper 12 closes. A part of the air flow is directed through the duct 13 past the heat exchanger 5, whereby it does not cool down, and after the heat exchanger 10 it is mixed with the air cooled in the heat exchanger. Thus, the desired temperature is easily achieved by adjusting the airflow ratio to suit.

Figures 1 and 2 show the heat exchanger as a conventional cross-flow counter-flow exchanger, but the invention 15 is of course not limited exclusively to this, and all generally known heat exchangers are possible. Figure 3 shows a solution in which the heat transfer takes place via a medium, for example water, which is circulated by the pump 15 through the heat exchangers 16 and 17. In this system, the control-20 damper has been replaced by a 3-way valve 18, which regulates the amount of circulating medium. Other control methods are of course possible, for example the speed of rotation of the pump 15 can be adjustable, a 3-way valve can be used, the amount of air 25 can be adjusted instead of water as in Fig. 1, etc.

Figure 4 shows a particularly preferred embodiment of the invention, in which the heat exchanger in winter is used for heat recovery from the exhaust air and in summer for cooling, and in which the humidification part is used for cooling and humidification in winter when the outdoor air is very dry.

The supply air duct 8 is connected to the humidification part 6 via a control damper 18 and after the humidification part 6 a connection 20 is established via the control damper 19 back to the supply air duct 35 8. The flow from the humidification part 6 to the heat exchanger 5 is regulated by a damper 67259, the flow rates passing by it are adjusted by means of dampers 23 and 24. The exhaust air passing the humidifying part 6 can in turn be led to the heat exchanger 5 via the control damper 25 or directly out through the control damper 26. 27 shows 5 auxiliary fans with their damper 28 and the damper 29 controls the amount of supply air going from the heat exchanger 5 directly to the space to be ventilated.

The operation of the system shown in Fig. 4 will be explained below.

10 In winter, when the heat exchanger 5 is used for heat recovery and the humidifying part 6 for humidifying the air conditioning air, the control dampers 21, 23, 26 and 28 are closed. The control dampers 24 and 25 are fully open, so that the exhaust air sucked from the air conditioning system of the exhaust fan 11a 4 flows through the dampers 15 24 and 25 to the heat exchanger 5, where the heat content of the exhaust air is transferred to the air conditioning air. The exhaust air then flows out. The air conditioning air is forced into the space to be ventilated by the fan 3 through the heat exchanger 5 and the control damper 29. If wetting is required, the damper 29 starts to close and the damper 18 and 19 start to open. Part of the air then flows through the damper 18 to the humidification part 6, where it is humidified. The humidified air is returned through the damper 19 and mixed with the air conditioning air after the damper 29. The desired degree of wetting is achieved by adjusting the ratio of the airflows flowing through the dampers 18 and 29.

When the outside temperature rises in spring (or autumn), the damper 25 starts to close and the damper 26 opens. In this case, the amount of exhaust air flowing through the heat exchanger 5 decreases, as a result of which the amount of heat transferred to the air-conditioning air decreases and the desired supply air temperature is reached despite the increase in the outdoor temperature. When the outdoor temperature rises to the same as the desired supply temperature, the damper 25 is closed. Also during this step, the humidification part 6 can be used for humidifying the supply air.

35 As the outside temperature continues to rise, the need for cooling begins to occur, at which point the damper 24 begins to close and the dampers 21 and 23 open. The dampers 18, 19 and 28 must then be closed, so that the system can no longer be used for humidification. However, it is usually not even necessary, because as the outdoor temperature rises, its water content increases, and as it cools, the relative humidity rises, so that, in general, sufficient relative humidity is obtained. When the dampers 21 and 23 open, part of the exhaust air flows to the humidifying part 6, where it cools, and further to the heat exchanger 5, where it cools the air conditioning air. When there is a need for Mak-10 sim cooling, damper 24 is fully closed and dampers 21 and 23 are fully open.

When the thermal load of the room to be ventilated is so high that the exhaust air temperature is higher than the outdoor air temperature, it is more preferable to use outdoor air 15 for cooling than exhaust air. This is made possible by the auxiliary fan 27. It can also increase the efficiency of the system so that the air volume of the auxiliary fan 27 is greater than that of the exhaust air fan 4, whereby the cooling capacity increases.

The system can be used firstly so that the auxiliary fan 27 of the 20 starts when the damper 23 is fully open, i.e. the cooling power is no longer sufficient to remove the air. When the fan 27 starts, the damper 23 must close and the damper 24 must open completely.

Another possibility is to use only outdoor air 25 for cooling. In this case, the fan 27 starts as soon as the need for cooling arises. Dampers 23 and 24 can then be omitted. Such an application is particularly useful when using the heat exchanger of Figure 3, since the outlet and the blow-in can be located 30 apart.

For the sake of clarity, the control system has been omitted from Figure 4, in principle it is similar to that shown in Figures 1 to 3. It consists of a thermostat which controls one or more actuators or other control devices, depending on the number of dampers.

What has been said in connection with Figures 1-3 about the various possibilities of variation is, of course, also true for the case of Figure 67. The arrangement of the components may be different from that shown in the figure, bypass control may be used, the type of heat exchanger may be of any known type, etc. Furthermore, any known humidification system may be used for humidification of the air. Naturally, parts of the system of Figure 4 can also be omitted. Instead of the purely outdoor cooling described above, only the cooling of the exhaust air can be used, in which case the fan 27 and the damper 28 10 are omitted. Likewise, the possibility of using humidification can be ruled out in winter, when dampers 18, 19, 21 and 29 are not required. All switching possibilities using the prior art are, of course, within the scope of the invention.

Claims (5)

67259 An air conditioning system in which the supply air (1) is passed through a heat exchanger (5) and the exhaust air (2) is led in the opposite direction through the same heat exchanger 5, characterized in that a humidification section (6) is arranged in the flow path before the heat exchanger (5). for cooling the air by evaporating steam therein and through which at least a part of the exhaust air (2) can be led, for cooling the supply air (1) in the heat exchanger (5) by means of the exhaust air (2). Air conditioning system according to Claim 1, characterized in that the cooling capacity is regulated by adjusting the mass flows involved in the heat exchange. Air conditioning system according to Claim 1, characterized in that the supply air duct (8) is provided with an adjustable connection (18) in front of the humidification section (6) so that at least part of the supply air after cooling in the humidification section (6) is available for cooling the supply air in a heat exchanger ( 5). Air conditioning system according to claim 3, characterized in that an adjustable connection (19, 20) is formed between the humidification part (6) and the heat exchanger (5) to the return duct (8) of the above-mentioned connection connected in front of the humidification part (6). (18) to use the humidification section (6) to at least partially humidify the supply air to the air-conditioned space. Air conditioning system according to Claims 3 and 4, characterized in that adjustable connections (24, 25-24, 26) are connected to the exhaust air duct 30 past the humidification part (6) to the heat exchanger (5) or to the outside, respectively.